Contact

Our key tasks

We are primarily tasked with providing power transmission services, system services and facilitating the energy market. Our core tasks follow from our appointment as grid operator under the Dutch 'Elektriciteitswet' (E-wet) and the German 'Energiewirtschaftsgesetz' (EnWG).

Our grid

TenneT manages the high-voltage grid in the Netherlands and large parts of Germany. TenneT transmits electricity at 110,000 volts (110 kV) and higher. With over 22,000 kilometres of high-voltage lines, we cross borders and connect countries.

Grid maps

Electricity market

The energy sector is developing rapidly. The process of European market integration began some years ago. Its purpose is to create a single European market that enables market parties to trade gas and electricity across national borders easily and efficiently.

Company

TenneT is a leading European electricity transmission system operator (TSO), with activities in the Netherlands and in Germany. We strive to ensure a reliable and uninterrupted supply of electricity in our high-voltage grid for some 41 million people.

Procurement

alpha ventus

Facts

Connection

66 km long and 62 MW capacity

6 km onshore cable

60 km offshore cable

Grid connection point

substation Hagermarsch (110 kV) Germany

Status of project

online since may 2009

About the project

alpha ventus

A few coastal offshore wind farms are implemented as AC connections. They are connected to the German grid via the nearest grid connection point. The first wind farm realised by TenneT for such a grid connection, was alpha ventus. This offshore test field is a joint venture of E.ON, EWE and Vattenfall, located 45 kilometres in linear distance to the coast of Borkum, an island in the North Sea.

Already in 2007, underground horizontal channels were drilled underneath the dunes and the mudflats along the coast of the North Sea island of Norderney for the connection of alpha ventus. In spring 2008, the 1.5 kilometres long ductworkwas completed in the soil of Norderney. At the same time the new Hagermarsch substation was erected onshore and connected to alpha ventus.

At the end of May 2008, the cables for the connection of alpha ventus were pulled in the empty conduit system. In summer 2008, the six kilometres of landcable as well as the 60 kilometres of subsea cable were installed.

Laying the cables in the North Sea confronts technology and employees with big challenges: Kilometres of cables weighing several tons have to be laid and installed by jetting up to three meters deep into the seabed. Depending on the characteristics of the sea bed the subsea cables were installed using various methods. The subsea cables weigh 53 kilogram per lineal meter.

This requires special ships which are capable of transporting the cable, previously wound onto enormous turntables, then paying it out into the sea. There are only few of these special ships which are capable of transporting several thousands of tons of cable.